2004 325xi losing coolant daily

[Nykie80538]

i have a coolant leak issue that we can not figure out. Approx 2 years ago the car over heated from the expansion tank cracking. We fixed that issue and drove the car with no issue for a bout a year, it then it
started to lose coolant over night. Every morning I would have to add coolant to the expansion tank. So we have replace the water pump, expansion tank twice, upper and lower hoses. We have done the pressure test with no signs of leaks. It does not appear that any coolant is in the oil. The other day we noticed that the coolant appeared to be coming from the upper radiator hose, where it connected to the radiator. So we replaced the radiator and the upper coolant hose again. And it is still leaking. Does anyone have similar problem or a solution to try?

[EdwardStewart]

Did you pressure test the cap? My sons was holding no pressure at all and leaking badly at times. Go back and grab the kit and test it!


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[EdwardStewart]

Also, have you tested at pressure for at least 20 minutes?


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[Nykie80538]

I'll have to ask my dad and see, they did it at the shop. I know that we have replaced the expansion tank twice and the cap at least once, hoping that would fix the problem, as it still continues to leak.

[Nykie80538]

Yes they tested it for an extended period of time

[EdwardStewart]

Ok, it sounds like they at least checked the cap. The expansion tank my son had was made in China and was 6 months old, it was leaking at the bottom where it clips onto the bracket that it is held onto. Is your car a manual or automatic?


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[EdwardStewart]

I replaced with OE along with the plastic piece that it fit into by the radiator, his is a manual. I did not notice this leak until we went to change the fluid as someone had put the wrong coolant in the car.


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[EdwardStewart]

As far as parts, who is sourcing the parts you are using? I have notice some serious issues with some aftermarket parts that are offered at discounted pricing to OE. Do you know where the parts are coming from?


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[EdwardStewart]

We own 2 2005 ZHP's and I have done all of the cooling maintenance on these car over the last few months.


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[MIKYZZ4]

I suspect the overheating episode has come back to haunt you.
Have a cylinder leakdown test performed with coolant level freshly topped off,
then watch for the bubbles!

[Nykie80538]

All of the parts have been ordered through my dad, who works for brake plus. I know that some have come out of Denver co, and some from BMW, as well as local parts stores

[EdwardStewart]

I suspect the overheating episode has come back to haunt you.
Have a cylinder leakdown test performed with coolant level freshly topped off,
then watch for the bubbles!

Excellent suggestion if everything else is checking out with standard pressure testing of the cooling system.


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[Honolulu]

Make sure that you are not trying to overfill the coolant reservoir. A friend had an '03 525i (528i?) and kept filling the reservoir right up, then getting anxious when the level was lower next time he opened the cap. RTFM! You don't fill the res to the rim, it'll puke out excess coolant.

But checking compression is also indicated, and looking for bubbles in the reservoir.